feat(mcp): add basic_memory_diagnostics tool for version and system info

Adds a new read-only MCP tool `basic_memory_diagnostics` that surfaces:
- Basic Memory package version and API version (from __init__.py)
- Python version and platform/architecture details
- Config file path and full config.json contents (cloud_api_key redacted)

Resolves #187.

Co-Authored-By: Claude <noreply@anthropic.com>
Signed-off-by: Drew Cain <groksrc@gmail.com>

src/basic_memory/mcp/tools/__init__.py

@@ -36,7 +36,11 @@ from basic_memory.mcp.tools.chatgpt_tools import search, fetch
 # Schema tools
 from basic_memory.mcp.tools.schema import schema_validate, schema_infer, schema_diff
 
+# Diagnostics tool
+from basic_memory.mcp.tools.basic_memory_diagnostics import basic_memory_diagnostics
+
 __all__ = [
+    "basic_memory_diagnostics",
     "build_context",
     "canvas",
     "cloud_info",

src/basic_memory/mcp/tools/basic_memory_diagnostics.py

@@ -0,0 +1,84 @@
+"""Diagnostic tool for Basic Memory version and system information."""
+
+import json
+import platform
+import sys
+
+import basic_memory
+from basic_memory.config import CONFIG_FILE_NAME, ConfigManager
+from basic_memory.mcp.server import mcp
+
+# Fields in BasicMemoryConfig that contain secrets and must never be surfaced.
+_SECRET_FIELDS = frozenset({"cloud_api_key"})
+
+
+def _redact_config(raw: dict) -> dict:
+    """Return a copy of the raw config dict with secret fields removed.
+
+    Only top-level keys are redacted. Nested secret-looking keys within
+    project entries are not currently present, but the pattern is explicit
+    so it is easy to extend.
+    """
+    return {k: v for k, v in raw.items() if k not in _SECRET_FIELDS}
+
+
+@mcp.tool(
+    "basic_memory_diagnostics",
+    annotations={"readOnlyHint": True, "openWorldHint": False},
+)
+def basic_memory_diagnostics() -> str:
+    """Return version, system, and configuration diagnostics for Basic Memory.
+
+    Provides:
+    - Basic Memory package version and API version
+    - Python version and platform details
+    - Config file path and its contents (secrets redacted)
+
+    Useful for troubleshooting installations and gathering information for
+    support requests. Read-only; never emits secrets or API keys.
+    """
+    # --- Version information ---
+    bm_version = basic_memory.__version__
+    api_version = basic_memory.__api_version__
+
+    # --- System information ---
+    python_version = sys.version
+    platform_info = platform.platform()
+    machine = platform.machine()
+
+    # --- Configuration ---
+    manager = ConfigManager()
+    config_file = manager.config_dir / CONFIG_FILE_NAME
+    config_exists = config_file.exists()
+
+    if config_exists:
+        try:
+            raw_config = json.loads(config_file.read_text(encoding="utf-8"))
+            safe_config = _redact_config(raw_config)
+            config_dump = json.dumps(safe_config, indent=2, default=str)
+        except Exception as exc:  # pragma: no cover
+            config_dump = f"<error reading config: {exc}>"
+    else:
+        config_dump = "<config file not found>"
+
+    lines = [
+        "# Basic Memory Diagnostics",
+        "",
+        "## Version",
+        f"- basic-memory: {bm_version}",
+        f"- API version: {api_version}",
+        "",
+        "## System",
+        f"- Python: {python_version}",
+        f"- Platform: {platform_info}",
+        f"- Architecture: {machine}",
+        "",
+        "## Configuration",
+        f"- Config path: {config_file}",
+        f"- Config exists: {config_exists}",
+        "",
+        "```json",
+        config_dump,
+        "```",
+    ]
+    return "\n".join(lines)